Caveats

When an object changes owner any listen registered with llGetOwner will not automatically update itself until the script is reset. The scripter can catch this scenario per the example below.

If a message satisfies the filters of multiple llListens registered by the script, only one event will be raised.

A prim cannot hear/listen to chat it generates.

The location of the listen is not at the listening prim's location but at the root prim's location. This is to deter people using child prims for spying over parcel boundaries. Chat generating functions on the other hand generate chat at the calling prim's location (and not at the root prim's location).

The above is not true for chat generated by avatars sitting on the same object as the listening prim.

Examples

Important: Please make sure that you close open listeners where possible. You'll make the Second Life experience so much better when paying attention to details here.

Trivial example to listen to any chat from the object owner and respond once. To reduce lag and avoid spamming surrounding users, it is vastly preferable to listen on channels other than 0 and to trigger the listen event by chatting on an alternative channel such as '/5 hello'.

// says beep to owner the first time owner says something in main chat;integer listen_handle;
default{state_entry(){//Registers the listen to the owner of the object at the moment of the call. This does not automatically update when the owner changes.// Change 0 to another positive number to listen for '/5 hello' style of chat.
listen_handle =llListen(0, "", llGetOwner(), "");
}listen(integer channel, string name, key id, string message ){llOwnerSay("beep");
// Stop listening until script is resetllListenRemove(listen_handle);
}changed(integer mask){//Triggered when the object containing this script changes owner.if(mask & CHANGED_OWNER){llResetScript(); // This will ensure the script listens to the new owner, and doesn't continue listening to the creator.}}}